Abdominal wall defects Flashcards
Anomalies associated with Pentalogy of Cantrell
Not every case will have all 5 abnl, and some cases may have assoc anomalies, usually midline defects such as cleft lip/palate, sirenomelia, exencephaly
Heart position in Pentalogy of Cantrell vs ectopia cordis
Heart in PoC is normally positioned within the chest, but with a subtle shift in axis.
Most common heart abnormality in Pentalogy of Cantrell, others?
Most common = VSD
Others = ASD, pulmonic stenosis, ToF, LV diverticulum
Other anomalies associated with Pentalogy of Cantrell
Vertebral and digital anomalies, including kyphoscoliosis and clinodactyly
Craniofacial - encephalocele, cleft lip, microphthalmia, low set ears
2VC
Absent left lung
Cloacal exstrophy
Fetal ascites
Ddx of Pentalogy of Cantrell
Ectopia cordis
Body-stalk anomaly
Simple omphalocele
Amniotic band syndrome
Management of pregnancy w/ Pentalogy of Cantrell
Estimate size and contents of omphalocele
Careful sono exam for other abnl
Karyotype
Surveillance for IUGR, PTL, rupture of omphalocele membrane
Reserve cesarean for obstetric indications, or if giant omphalocele
Genetics of Pentalogy of Cantrell
Primarily thought to be sporadic
Chrom abnl not usual, but abnl in 13 & 18 reported
Possible X-linked
What is an omphalocele?
Defect in ventral abdominal wall characterized by absence of abdominal muscles, fascia, skin. Defect is covered by a membrane that consists of peritoneum and amnion.
Where does the umbilical cord insert in omphalocele?
Insets into the membrane at a location distant from the abdominal wall.
Why and when does omphalocele occur?
Abnormality during process of body infolding at 3-4 weeks gestation.
Incidence of omphalocele
1/4000-7000 livebirths, 1/300-400 combined livebirths & stillbirths
Epidemiology of omphalocele
Associated with AMA
Ruptured omphalocele vs gastroschisis
Defects are usually larger with ruptured omphalocele and have at least exposed, if not extracorporeal, liver
What is Beckwith-Wiedemann syndrome?
Aka exomphalos-macroglossia-gigantism syndrome. Consists of omphalocele, visceromegaly, macroglossia, and severe neonatal hypoglycemia.
Cardiac abnl frequent.
Malignant tumors in 10% - Wilm’s tumor, hepatoblastoma, adrenal tumors
Macroglossia & visceral enlargement rarely seen prior to 3rd trimester.
Frequency of visceral malformations with omphalocele
50-70% of cases
Frequency of chromosomal abnl w/ omphalocele
30-60%
The absence of liver in the omphalocele increases or decreases the likelihood of chromosomal abnl & perinatal mortality?
Interestingly, it increases the likelihood. (In other words, small defects are associated with an increased risk of chromosomal abnl).
Predominant chromosomal abnl w/ omphalocele
T18 (17 of 19 cases w/ chrom abnl in one series)
Risk of chromosomal abnl in central vs epigastric omphalocele
Central - 70%
Epigastric - 12%
Risk of associated anomalies in omphalocele
65% of 349 cases detected antenatally
Risk of associated anomalies in omphalocele w/ a nl karyotype
56.00%
Incidence of associated congenital heart disease w/ omphalocele
25.00%
Does MSAFP have a higher sensitivity for omphalocele or gastroschisis?
Much higher for gastroschisis (for cutoff of >2.5 MoM and >3.0 MoM, detection rates were 98% and 96% for gastroschisis, and 71% and 65% for omphalocele).
Management of pregnancy w/ omphalocele
Estimate size and contents of omphalocele, location of cord insertion relative to herniation, presence of amnioperitoneal membrane
Careful sono exam for other abnl, including fetal echo
Chromosomal analysis
Consultation with pedi surgery, genetics, neonatology, pedi cards
Surveillance for IUGR (6-35%) & PTL (25-65%), and for omphalocele rupture
Risk of significant pulmonary hypoplasia and pulmonary hypertension w/ omphalocele
Up to 50%. Fetology recommends MRI for lung volume assessment at 32-34w.
Mode of delivery w/ omphalocele
Controversial. If small, Fetology recommends vaginal delivery. If giant (>5 cm) or extracorporeal liver, then CD may be necessary to avoid dystocia.
Recurrence risk of omphalocele
Depends on cause:
If T18, then 1% or age-related maternal risk, whichever is higher
IF Beckwith-Wiedemann - may be as high as 50%
If isolated - generally considered sporadic, but at least 17 cases of familial omphalocele have been described (?AD)
What is gastroschisis?
An isolated abdominal wall defect to the right of normally inserted umbilical cord, usually 2-3 cm in diameter
Why and when does gastroschisis occur?
Occurs secondary to incomplete closure of the lateral folds during the 6th week of gestation
How does the eviscerated bowel from gastroschisis look at birth? Why?
Has a thick, edematous appearance described as a “peel”. The peel involves the serosa and is composed of fibrinand collagen. Thought to be caused by an inflammatory rxn due to amniotic fluid exposure, combined with constriction at the abdominal wall defect.
Epidemiology of gastroschisis
Young maternal age - fourfold increased risk
Cigarette use - 2.1-fold greater risk
?Seasonal variation - deliveries in 1st quarter of the year
Methamphetamine & cocaine use
Normal events of bowel migration
The midgut that will normally form the small bowel, cecum, ascending and proximal transverse colon is connected to the yolk sac
This connection is reduced to a narrow yolk stalk as the amniotic cavity expands and yolk sac is pulled away from embryo
The mesentery suspending the midgut rapidly elongates, and a U-shaped loop of midgut herniates into umb cord
The loop then rotates 90 degrees counterclockwise about the SMA
By 11w, the loops return to the abd cavity by rotating counterclockwise another 180 degrees
By what GA should the bowel be completely intra-abdominal?
12 weeks. Earliest diagnosis of gastroschisis was 12w 3d.
